Process for the protection of a metal ingot against oxidation

Abstract

A process for reducing the degree of oxidation of a metal obtained by a production or purification operation wherein the metal is converted to the vapor state and then condensed to the liquid form in a vessel the lower part of which forms a crucible or pot in which it solidifes and in which a fusible flux is added to the metal in the crucible with a view to reducing the degree of oxidation, whereby the flux is added after previously being melted and the molten flux caused to penetrate into the void formed by contraction between the ingot and the inner wall of the crucible or pot.

I claim: 
     
       1. A method to reduce the degree of oxidation of an ingot of a metal comprising magnesium obtained by a production or purification operation by converting the metal to a vapor state, condensing the vapor to the liquid form in a vessel the lower portion of which forms a crucible in which the liquid solidifies as an ingot with the formation of space by contraction between the ingot and the inner walls of the crucible, adding a fusable flux to the metal in the crucible with a view towards reducing the degree of oxidation, comprising causing a molten flux to flow into the said space between the crucible walls and the adjacent surfaces of the ingot and over the top of the ingot. 
     
     
       2. The method as claimed in claim 1 in which the ingot is formed with a concave top surface and the flux is introduced onto the top surface and which includes the step of inclining the crucible to cause the liquid flux to overflow the edges of the ingot into the said space. 
     
     
       3. The method as claimed in claim 1 in which the ingot is formed with a concave top surface and the flux is introduced onto the top surface of the ingot, said ingot being formed with one or more passages extending from the concave portion of the top surface to the said space, at a level below the upper edge of the ingot, to enable liquid flux to flow from the concave portion of the ingot to the said space. 
     
     
       4. The method as claimed in claim 1 in which the liquid flux is guided by a distributor over the top of the ingot to the entry into said space for flow of the liquid flux directly into said space.